/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.ssi;

import java.io.PrintWriter;

/**
 * Return the result associated with the supplied Server Variable.
 *
 * @author Bip Thelin
 * @author Paul Speed
 * @author Dan Sandberg
 * @author David Becker
 */
public class SSIEcho implements SSICommand {
	protected static final String DEFAULT_ENCODING = "entity";
	protected static final String MISSING_VARIABLE_VALUE = "(none)";

	/**
	 * @see SSICommand
	 */
	@Override
	public long process(SSIMediator ssiMediator, String commandName,
	                    String[] paramNames, String[] paramValues, PrintWriter writer) {
		String encoding = DEFAULT_ENCODING;
		String originalValue = null;
		String errorMessage = ssiMediator.getConfigErrMsg();
		for (int i = 0; i < paramNames.length; i++) {
			String paramName = paramNames[i];
			String paramValue = paramValues[i];
			if (paramName.equalsIgnoreCase("var")) {
				originalValue = paramValue;
			} else if (paramName.equalsIgnoreCase("encoding")) {
				if (isValidEncoding(paramValue)) {
					encoding = paramValue;
				} else {
					ssiMediator.log("#echo--Invalid encoding: " + paramValue);
					writer.write(errorMessage);
				}
			} else {
				ssiMediator.log("#echo--Invalid attribute: " + paramName);
				writer.write(errorMessage);
			}
		}
		String variableValue = ssiMediator.getVariableValue(
				originalValue, encoding);
		if (variableValue == null) {
			variableValue = MISSING_VARIABLE_VALUE;
		}
		writer.write(variableValue);
		return System.currentTimeMillis();
	}

	protected boolean isValidEncoding(String encoding) {
		return encoding.equalsIgnoreCase("url")
				|| encoding.equalsIgnoreCase("entity")
				|| encoding.equalsIgnoreCase("none");
	}
}